Genotypes were determined for 410 subjects. The PREST software program, which assesses degree of allele sharing among relative-pairs, was used to identify potential errors in pedigree structure (McPeek and Sun, 2000). Six individuals were identified as problematic and removed from further analyses. Pedcheck was then used to detect non-Mendelian inheritance patterns (O’Connell and Weeks, 1998). When a Mendelian inconsistency was observed, genotypes for the nuclear family at that polymorphism were removed. This resulted in the removal of 772 genotypes. To further reduce errors, the maximum-likelihood error-checking algorithm implemented in Merlin (Abecasis et al., 2002) was used to identify genotypes that had a probability of less than 0.025 of being correct. A total of 508 genotypes were removed in this step. Ultimately 273,598 genotypes were accepted.
